Devices and methods for controlling expandable prostheses during deployment

ABSTRACT

Prosthesis delivery devices and methods are provided that enable precise control of prosthesis position during deployment. The prosthesis delivery devices may carry multiple prostheses and include deployment mechanisms for delivery of a selectable number of prostheses. Control mechanisms are provided in the prosthesis delivery devices that control either or both of the axial and rotational positions of the prostheses during deployment. This enables the deployment of multiple prostheses at a target site with precision and predictability, eliminating excessive spacing or overlap between prostheses. In particular embodiments, the prostheses of the invention are deployed in stenotic lesions in coronary or peripheral arteries or in other vascular locations.

BACKGROUND OF THE INVENTION

Stents are tubular prostheses designed for implantation in a vessel tomaintain patency of the vessel lumen. Stents are used in various vesselsthroughout the body, including the coronary arteries, femoral arteries,iliac arteries, renal artery, carotid artery, vascular grafts, biliaryducts, trachea, and urethra, to name some examples. Stents are typicallyimplanted by means of long and flexible delivery catheters that carrythe stents in a compact, collapsed shape to the treatment site and thendeploy the stents into the vessel. In some applications, balloonexpandable stents are used. These stents are made of a malleable metalsuch as stainless steel or cobalt chromium and are expanded by means ofa balloon on the tip of the delivery catheter to plastically deform thestent into contact with the vessel wall. In other applications,self-expanding stents are used. These are made of a resilient materialthat can be collapsed into a compact shape for delivery via catheter andthat will self-expand into contact with the vessel when deployed fromthe catheter. Materials commonly used for self-expanding stents includestainless steel and elastic or superelastic alloys such as nickeltitanium (Nitinol™).

While self-expanding stents have demonstrated promise in variousapplications, such stents face a number of challenges. One suchchallenge is that in some cases the disease in a vessel may be soextensive that a stent of very long length, e.g. 30-200 mm, is calledfor. Currently available stents are typically less than 30 mm in length,and suffer from excessive stiffness if made longer. Such stiffness isparticularly problematic in peripheral vessels such as the femoralarteries, where limb movement requires a high degree of flexibility inany stent implanted in such vessels.

To overcome the stiffness problem, the idea of deploying multipleshorter stents end-to-end has been proposed. However, this approach hassuffered from several drawbacks. First, currently available deliverycatheters are capable of delivering only a single stent per catheter. Inorder to place multiple stents, multiple catheters must be inserted,removed and exchanged, heightening risks, lengthening procedure time,raising costs, and causing excessive material waste. In addition, thedeployment of multiple stents end-to-end suffers from the inability toaccurately control stent placement and the spacing between stents. Thisresults in overlap of adjacent stents and/or excessive space betweenstents, which is thought to lead to complications such as restenosis,the renarrowing of a vessel following stent placement. Withself-expanding stents the problem is particularly acute because as thestent is released from the catheter, its resiliency tends to cause it toeject or “watermelon seed” distally from the catheter tip by anunpredictable distance. During such deployment, the stent may displacenot only axially but rotationally relative to the delivery catheterresulting in inaccurate, uncontrollable, and unpredictable stentplacement.

Interleaving stents or stent segments such as those disclosed inco-pending application Ser. No. 10/738,666, filed Dec. 16, 2003, whichis incorporated herein by reference, present even greater challenges toconventional delivery systems. Interleaving stents have axiallyextending elements on each end of the stent that interleave with similarstructures on an adjacent stent. Such interleaving minimizes the gapbetween adjacent stents and increases vessel wall coverage to ensureadequate scaffolding and minimize protrusion of plaque from the vesselwall. However, such interleaving requires that the relative rotationalas well as axial positions of the adjacent stents be maintained duringdeployment to avoid metal overlap and excessive gaps between stents.Conventional delivery systems suffer from the inability to control boththe axial and rotational positions of self-expanding stents as they aredeployed.

What are needed, therefore, are stents and stent delivery system thatovercome the foregoing problems. In particular, the stents and stentdelivery systems should facilitate stenting of long vascular regions ofvarious lengths without requiring the use of multiple catheters. Suchstents and delivery systems should also provide sufficient flexibilityfor use in peripheral vessels and other regions where long and highlyflexible stents might be required. In addition, the stents and stentdelivery systems should enable the delivery of multiple stents ofvarious lengths to one or more treatment sites using a single catheterwithout requiring catheter exchanges. Further, the stents and stentdelivery systems should facilitate accurate and repeatable control ofstent placement and inter-stent spacing to enable deployment of multipleself-expanding stents end-to-end in a vessel at generally constantspacing and without overlap. Moreover, the stents and delivery systemsshould enable the deployment of interleaving stents or stent segmentswith precision and control over both the axial spacing and rotationalposition of each stent or segment.

BRIEF SUMMARY OF THE INVENTION

The present invention provides prostheses, prosthesis delivery systems,and methods of prosthesis deployment that enable the precise andcontrollable delivery of multiple prostheses using a single deliverycatheter. The prostheses, delivery systems, and methods of the inventionprovide for the precise control of prosthesis placement so thatinter-prosthesis spacing is maintained at a constant and optimumdistance. In some embodiments, both axial and rotational displacement ofthe prostheses relative to the delivery catheter is controlled duringdeployment, enabling the delivery of multiple prostheses that interleavewith one another without overlap. The prostheses, prosthesis deliverysystems, and methods of the invention further enable the length ofprostheses to be customized in situ to match the length of the site tobe treated. The invention is particularly useful for delivery ofself-expanding prostheses, but balloon expandable prostheses are alsocontemplated within the scope of the invention. The invention iswell-suited to delivery of stents to the coronary arteries and toperipheral vessels such as the popliteal, femoral, tibial, iliac, renal,and carotid arteries. The invention is further useful for delivery ofprostheses to other vessels including biliary, neurologic, urinary,reproductive, intestinal, pulmonary, and others, as well as for deliveryof other types of prostheses to various anatomical regions, whereverprecise control of prosthesis deployment is desirable.

In a first aspect of the invention, a prosthesis delivery catheterincludes an outer shaft having a first lumen; a plurality ofself-expanding tubular prostheses carried within the first lumen, theprostheses being adapted to radially expand upon deployment from thefirst lumen; a deployment mechanism for deploying a selected number ofthe prostheses from the first lumen; and a control member interactivewith the prostheses to control expansion of the prostheses when theprostheses are deployed from the first lumen.

The control member may comprise a plurality of axially-extending wires,the prostheses being coupled to the wires and axially slidable thereon,the wires being radially deflectable to allow controlled expansion ofthe prostheses. The wires may have free distal ends configured to moveradially outward as the prostheses expand. The distal ends of the wiresmay be retractable into the outer shaft following deployment of theselected number of prostheses. The prostheses may have sidewalls with aplurality of openings, the wires being threaded through the openings.The wires may form a loop extending around the outside of the prosthesesand through the inside of the prostheses, wherein the wires can bewithdrawn from around the prostheses following deployment thereof. Insuch case, at least one end of each wire is releasable to allow the wireto be withdrawn following prosthesis deployment.

The delivery catheter may further comprise an inner shaft disposed inthe first lumen, the prostheses being slidably disposed around the innershaft, wherein a distal end of each wire is releasably coupled to theinner shaft. A nosecone may be attached to the inner shaft distally ofthe prostheses, the distal end of each wire being releasably coupled tothe nosecone. The inner shaft may also have an inner lumen and at leastone port in communication with the inner lumen, wherein the controlwires are slidably disposed through the inner lumen and the port.

The control member may also comprise a sleeve disposed around theprostheses, the sleeve being expandable to allow controlled expansion ofthe prostheses. The sleeve may be elastomeric, an expandable mesh orwoven material, or other expandable structure. When expanded, the sleevemay form a cone shape that flares in the distal direction. The sleevemay be slidable relative to the outer shaft. The sleeve may have atleast one longitudinal slit therein whereby it expands by splitting atthe longitudinal slit. The sleeve may have a pair of opposing edgesbordering the longitudinal slit, a cone shape being formed by moving theedges at an angle relative to each other. The sleeve may also have aplurality of longitudinal sections or beams separated by longitudinalslits, the longitudinal sections being deflectable outwardly to allowcontrolled expansion of the prostheses. A retainer may be releasablycoupled to the longitudinal sections to selectively prevent radialdeflection thereof. The retainer may comprise a capsule coupled to aninner shaft slidably disposed through the first lumen, longitudinalsections being received in the capsule.

The deployment mechanism of the delivery catheter may comprise a pushingelement slidably disposed in the first lumen, the pushing element beingin engagement with at least one of the prostheses to advance theprostheses distally relative to the outer shaft. In preferredembodiments, the prostheses are self-expandable, made of resilient orshape memory materials such as stainless steel, Nitinol or suitablepolymers. Such self-expanding prostheses are held in an unexpanded statewithin the outer shaft until deployed therefrom, whereupon theyresiliently expand to an expanded shape in contact with the vessel wallor lesion. The delivery systems of the invention will also be usefulwith balloon expandable prostheses. In either case, expandable balloons,valve members, and other mechanisms may also be included in the deliverycatheter to facilitate stent deployment.

In a further aspect of the invention, the prostheses are releasablyinterconnected to each other. In this case, the control member maycomprise an interconnection structure on the pushing element, theinterconnection structure being releasably coupled to at least one ofthe prostheses to resist distal movement of the prostheses relative tothe outer shaft.

In addition to controlling axial position of the stents relative to thedelivery catheter and/or to each other during deployment, the controlmember of the delivery catheter is preferably configured to maintainrotational position of the prostheses relative to each other. Thisfacilitates the delivery of stents having axially interleaving elementsand prevents excessive spacing or overlap between such elements

In still another aspect of the invention, a prosthesis delivery catheterfor delivering prostheses into a vessel lumen comprises an outer shafthaving a first lumen; a plurality of self-expanding tubular prosthesescarried within the first lumen, the prostheses being adapted to radiallyexpand upon deployment from the first lumen; a deployment mechanism fordeploying a selected number of the prostheses from the first lumen; andan anchor member adapted to engage the vessel to limit movement of theouter shaft relative thereto when a prosthesis is being deployed. In oneembodiment, the anchor member comprises an expandable member mounted onan inner shaft, the inner shaft being slidably disposed in the firstlumen. The expandable member preferably comprises a balloon. Theexpandable member may be configured to expand within a deployedprosthesis in the vessel lumen. The expandable member is preferablyconfigured to remain expanded within the deployed prosthesis while asecond prosthesis is deployed adjacent to the deployed prosthesis. Thismaintains the relative positions of the deployed prosthesis and thedelivery catheter so the second prosthesis is deployed at a predictabledistance from the deployed prosthesis.

In another aspect of the invention, a prosthesis delivery catheter fordelivering prostheses into a vessel lumen comprises an outer shafthaving a first lumen; a plurality of self-expanding tubular prosthesescarried within the first lumen, the prostheses being adapted to radiallyexpand upon deployment from the first lumen, each prosthesis comprisinga distal portion and proximal portion, the distal portion beingconfigured to expand into engagement with the vessel while the proximalportion is at least partially disposed in the first lumen; and adeployment mechanism for deploying a selected number of the prosthesesfrom the first lumen. Preferably, the distal portion is configured toengage the vessel prior to deployment of the proximal portion so thatthe prosthesis remains in a generally constant position relative to thecatheter as the proximal portion is deployed.

In one embodiment, the distal and proximal portions of the prosthesesare interconnected by at least one spring member, the spring memberhaving a retracted shape and an elongated shape and being biased intothe retracted shape, wherein deployment of the distal portion into thevessel elongates the spring into the elongated shape. In such a case,the deployment of the proximal portion into the vessel allows the springto return at least partially to the retracted shape to draw the proximalportion toward the distal portion.

In still another aspect, the invention provides a method of deliveringone or more prostheses to a treatment site in a vessel comprisingpositioning a delivery catheter at the treatment site, the deliverycatheter carrying a plurality of self-expanding prostheses; selecting adesired number of the prostheses to deploy; deploying the desired numberof prostheses from the delivery catheter into the vessel, eachprosthesis expanding into contact with the vessel upon deployment; andcontrolling the axial displacement of each of the selected number ofprostheses relative to the delivery catheter during the deploymentthereof.

In one embodiment, the axial displacement is controlled by an expandablesleeve disposed around the desired number of prostheses. The method mayfurther include retracting the sleeve from around the prostheses afterthe prostheses have been deployed. The axial displacement may also becontrolled by a plurality of wires coupled with the desired number ofprostheses. The wires may be threaded through openings in each of theprostheses, and may be retracted from the prostheses after theprostheses have been deployed.

The method may further include controlling the rotational displacementof the selected number of prostheses relative to the delivery catheterand/or relative to each other during the deployment thereof.

The axial displacement of the prostheses may be controlled by expandingan expandable member in the vessel during deployment of at least aportion of the desired number of prostheses. Alternatively, the axialdisplacement may be controlled by first expanding a distal portion of afirst of the prostheses into engagement with the vessel while a proximalportion of the first of the prostheses remains in the delivery catheter,then expanding the proximal portion of the first of the prostheses intoengagement with the vessel.

As a further alternative, the prostheses may be releasablyinterconnected while in the delivery catheter, wherein the axialdisplacement is controlled by connecting at least one of the prosthesesto a restraining member in the delivery catheter. In this case, theselected number of prostheses becomes detached from the prosthesesremaining in the delivery catheter upon deployment.

Further aspects of the nature and advantages of the invention will beapparent from the following detailed description of various embodimentsof the invention taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cut-away view of a prosthesis delivery catheteraccording to the invention.

FIG. 2A is a side cross-sectional view of a distal portion of aprosthesis delivery catheter according to the invention in a furtherembodiment thereof.

FIG. 2B is a side cross-sectional view of the prosthesis deliverycatheter of FIG. 2A showing the deployment of prostheses in a vessel.

FIGS. 3A-3C are perspective, side, and end views respectively of aprosthesis coupled to control wires according to further embodiments ofthe invention.

FIG. 4A is a side cross-section of a distal portion of a prosthesisdelivery catheter according to the invention in a further embodimentthereof.

FIG. 4B is a side cross-section of the prosthesis delivery catheter ofFIG. 4A showing the deployment of prostheses in a vessel.

FIG. 5 A is a side cross-section of a distal portion of a prosthesisdelivery catheter according to the invention in a further embodimentthereof.

FIG. 5B is an oblique view of a distal portion of a prosthesis deliverycatheter according to the invention in yet another embodiment thereof.

FIGS. 6A-6C are side cross-sectional views of a distal portion of aprosthesis delivery catheter according to the invention in still anotherembodiment thereof, showing the outer shaft unretracted, outer shaftretracted with sleeve unexpanded, and sleeve with stents expanded,respectively.

FIGS. 7A-7B are side cross-sectional views of a distal portion of aprosthesis delivery catheter according to the invention in anotherembodiment thereof, showing outer shaft retracted with sleeveunexpanded, and outer shaft retracted with sleeve and stents expanded,respectively.

FIGS. 8A-8C are side cross-sectional views of a distal portion of aprosthesis delivery catheter according to the invention in a furtherembodiment thereof, showing the outer shaft unretracted, outer shaftretracted with sleeve unexpanded, and sleeve with stents expanded,respectively.

FIGS. 9A-9B are side cross-sectional views of a distal portion of aprosthesis delivery catheter in a vessel according to the invention inanother embodiment thereof, showing outer shaft retracted withprosthesis partially deployed, and prosthesis fully deployed,respectively.

FIGS. 10A-10B are side cross-sectional views of a distal portion of aprosthesis delivery catheter in a vessel according to the invention inyet another embodiment thereof, showing outer shaft retracted withprosthesis partially deployed, and prosthesis fully deployed,respectively.

FIGS. 11A-11C are side cross-sectional views of a distal portion of aprosthesis delivery catheter in a vessel according to the invention inyet another embodiment thereof, showing a first prosthesis deployed, anexpandable member expanded within the first prosthesis, and a secondstent deployed with expandable member expanded in the first prosthesis,respectively.

FIGS. 11D-11F are side cross-sectional views of a distal portion of aprosthesis delivery catheter according to the invention in anotherembodiment thereof, showing the delivery catheter prior to stentdeployment, the deployment of a first prosthesis in a vessel, and adeployed prosthesis in the vessel, respectively.

FIG. 12 is a side cross-sectional view of a distal portion of aprosthesis delivery catheter in a vessel according to the invention instill another embodiment thereof, showing a first prosthesis deployed ina lesion.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a first embodiment of a prosthesis deliverycatheter according to the invention is illustrated. Delivery catheter 20may have any of various constructions, including that described inco-pending application Ser. No. 10/637,713, filed Aug. 8, 2003 (AttorneyDocket No. 21629-000340), which is incorporated herein by reference.Delivery catheter 20 has a handle assembly 21 and an elongated catheterbody 22 that includes three concentric tubular shafts all axiallyslidable relative to one another: an outer shaft 24, a pusher 26, and aninner shaft 28. Pusher 26 has a distal extension 27 to which a pusherring 29 is fixed. In a distal region of the catheter body 22, aguidewire tube 30 extends slidably through a port 32 in outer shaft 24and through pusher ring 29 and has a distal end 34, to which is mounteda nosecone 36 and a stop member 38.

Delivery catheter 20 further includes one or more stent expansioncontrol members, which in the illustrated embodiment comprise aplurality of control wires 40. Preferably, one or more pairs of controlwires 40 are mounted on opposing sides of delivery catheter 20, e.g.four control wires 40 offset 90° from each other. Control wires 40 arefixed at their proximal ends 42 to inner shaft 28, and have free distalends 44.

Outer shaft 24 has a distal extremity 46 defining a first lumen 48. Aplurality of stents 50 are disposed in a collapsed configuration withinfirst lumen 48. Stents 50 are preferably composed of a resilientmaterial such as stainless steel or Nitinol so as to self-expand fromthe collapsed configuration to a radially expanded configuration whendeployed from first lumen 48. While stents 50 as illustrated have awave-like or undulating pattern in a plurality of interconnectedcircumferential members, the pattern illustrated is merely exemplary andthe stents of the invention may have any of a variety of strut shapes,patterns, and geometries. From 2 up to 10 or more stents may be carriedby outer shaft 24. Optionally, a valve member 49 is mounted within firstlumen 48 to facilitate separating those stents 50 to be deployed fromthose to remain within outer shaft 24, as described in co-pendingapplication Ser. No. 10/412,714, filed Apr. 10, 2003, which isincorporated herein by reference.

Control wires 40 run along the outside of stents 50 or through theinterior of stents 50, are threaded through openings in the walls ofstents 50 or are otherwise coupled with stents 50 to control thedeployment thereof, as described more fully below. Control wires 40 arecomposed of a resilient material such as stainless steel, Nitinol, or asuitable polymer, and are preferably generally straight and biasedinwardly against guidewire tube 32 or to a position generally parallelto the axial direction. In FIG. 1, outer shaft 24 has been retracted toexpose a plurality of stents 50 which are partially expanded and remaincoupled to or restrained by control wires 40, as explained in greaterdetail below.

Handle assembly 21 has a rotatable retraction knob 52 coupled to a shafthousing 53, to which outer shaft 24 is fixed. By rotating retractionknob 52, outer shaft 24 may be retracted proximally relative to pusher26 and inner shaft 28. A pull ring 54 is coupled to inner shaft 28,allowing inner shaft 28, and hence control wires 40, to be retractedproximally relative to outer shaft 24. A switch 56 engages anddisengages pusher 26 with outer shaft 28, so that pusher 26 either moveswith outer shaft 24 or remains stationary as outer shaft 24 isretracted. Indicia 58 on shaft housing 53 indicate the extent ofretraction of outer shaft 28 by distance, number of stents, or othersuitable measure. Other aspects of handle assembly 21 are described inco-pending application Ser. No. 10/746466, filed Dec. 23, 2003 (AttorneyDocket No. 21629-002200), which is incorporated herein by reference.Except as stated otherwise, any of the embodiments of the stent deliverycatheter described below may incorporate the features and be otherwiseconstructed as just described.

FIGS. 2A-2B illustrate a distal extremity of a stent delivery catheter60 according to the invention in a further embodiment thereof. In thisembodiment, stents 62 have a series of diamond shaped openings 64 in thewalls thereof through which a plurality of control wires 66 arethreaded. Stents 62 have a plurality of axially-extending V-shapedpoints 63 on their distal and proximal ends. These points 63 areconfigured to interleave or nest with the points 63 on the adjacentstent 62, preferably both in the collapsed and expanded configurations.Various suitable interleaving stent geometries are described inco-pending application Ser. No. 10/736,666, filed Dec. 16, 2003, whichis incorporated herein by reference. In order to maintain thisinterleaving, it is important to maintain the relative rotational andaxial positions of the adjacent stents 62 both before and duringdeployment. By extending through the openings 64 in each stent, controlwires 66 keep adjacent stents 62 in rotational alignment as they areadvanced forward through the catheter and during deployment. Preferably,each control wire 66 is threaded through at least two openings 64 ineach stent 62, one opening 64 a near the distal end of each stent 62 andone opening 64 b near the proximal end of each stent 62. Alternatively,control wires 66 may be threaded through only a single opening 64 orthrough three or more openings 64 on each stent 62. Preferably, however,control wires 66 are threaded so that the distal and proximal ends ofstents 64 will expand at a generally uniform rate when released, asdescribed below.

Control wires 66 are constructed of a resilient and flexible metal orpolymer with sufficient stiffness to provide controlled resistance tothe expansion of stents 62. This stiffness may be selected to allow thedesired expansion behavior of stents 62 such that “watermelon seeding”is avoided, inter-stent spacing is maintained, and sufficient stentexpansion occurs. Control wires 66 may have various cross-sectionalgeometries, and may be a flat ribbons or blades, round or oval wires,I-beams, or other suitable structures to control stent expansion,maintain spacing and rotational position, and facilitate withdrawal fromstents 62 without interference. Control wires 66 may be composed of orcoated with a lubricious material such as PTFE to reduce friction duringremoval from stents 62. In other embodiments, control wires 66 may havesurface features, be wrapped with wire windings, or be coated with“sticky” material to increase friction with stents 62. Coatings orsurface structures such as scales with one-way frictional effects mayalso be applied to control wires 66.

As a further alternative, control wires 66 may comprise flexible hollowtubes which are pneumatically or hydraulically controllable to varytheir rigidity or stiffness. For example, control wires 66 may comprisepolymeric tubes that radially contract or flatten and are very flexiblewhen evacuated of fluid, but which become more rigid when filled withpressurized fluid, such as saline, air, or other liquid or gas. In suchan embodiment, control wires 66 are fluidly connected to a pump,syringe, or other suitable fluid delivery mechanism at the proximal endof the delivery catheter. In this way, control wires 66 may bepressurized to increase stiffness as stents 62 are deployed, thenevacuated of fluid to reduce their profile and stiffness duringwithdrawal from the deployed stents.

Stents 62 are slidably positioned over an inner shaft 68, to which isattached a nosecone 70 at the distal end of the device. An outer shaft72 is slidably disposed over inner shaft 68 and surrounds stents 62,maintaining them in a collapsed configuration, as shown in FIG. 2A. Apusher shaft 74 is slidably disposed over inner shaft 68 and isconfigured to engage the proximal end of the proximal-most stent 62.Outer shaft 72 is retractable relative to inner shaft 68 in order toexpose a desired number of stents 62 as shown in FIG. 2B. When outershaft 72 is retracted, the exposed stents 62 self-expand to alarger-diameter expanded shape in engagement with lesion L in vessel V.Preferably, at least the distal end of the distal-most stent 62, andmore preferably a substantial portion of all stents 62 being deployed,is allowed to expand into engagement with lesion L while control wires66 remain threaded through openings 64. Control wires 66 are thenwithdrawn from openings 62, preferably by holding catheter 60 inposition and pulling control wires 66 proximally using a suitablemechanism such as that described above with reference to FIG. 1.Alternatively, the entire catheter 60 may be retracted proximallyrelative to stents 62 to withdraw control wires 66 from openings 62.Because at least a portion of stents 62 is in engagement with lesion L,stents 62 are held in position in the vessel as control wires 66 arewithdrawn.

Optionally, inner shaft 68 may have a balloon 76 mounted thereto nearits distal end to enable pre- or post-dilatation of lesion L. In thisembodiment, inner shaft 68 has an inflation lumen through whichinflation fluid may be delivered to balloon 76. Balloon 76 is preferablyas long as the longest lesion that might be treated using catheter 60.To dilate lesion L prior to stent deployment, or to further expandstents 62 after deployment, outer shaft 72 and those of stents 62remaining therein are retracted relative to inner shaft 68 to expose adesired length of balloon 76. The exposed portion of balloon 76 may thenbe inflated within the lesion L and/or the deployed stents 62.

Following deployment and any post-dilatation, inner shaft 68 isretracted into outer shaft 72 while maintaining pressure against pushershaft 74. This slides stents 62 distally along control wires 66 andrepositions stents 62 to the distal end of inner shaft 68 so as to beready for deployment. Catheter 60 may then be repositioned to anothervascular location for deployment of additional stents 62.

Control wires 66 may be coupled to stents 62 in various ways, some ofwhich depend upon the configuration of stents 62. For example, as shownin FIGS. 3A-B, the points 63 at the ends of each stent 62 may be bentinwardly such that a portion of the openings 64′ are oriented axially.Control wires 66 may then be threaded through these axially-orientedopenings 64′. Preferably, upon deployment, points 63 are adapted todeform with stent expansion so as to be more parallel to the axialdirection, thereby providing a smooth and open flow path through thestent.

In another embodiment, shown in FIG. 3C, stents 80 have axially-alignedeyelets 82 through which control wires 84 are threaded. These eyelets 82may be in the interior of stents 82 as shown in FIG. 3C, or such eyeletsmay be on the exterior surface of stents 82, or could be drilled throughone or more of the struts of stents 82. Various other structures mayalso be used for coupling the stents of the invention to control wires,including hooks, channels, holes, sleeves, and others, disposed on theinterior, exterior or end surfaces of the stent, or through the strutsthemselves. Such structures may by integral with stent struts and of thesame material, may be attached to the stent struts and be of same ordifferent material, or may be a biodegradable material that erodes andeventually is absorbed into the body following deployment.

Referring now to FIGS. 4A-4B, in a further embodiment, a stent deliverycatheter 90 has an outer shaft 92 slidably disposed over an inner shaft94, and at least one stent 96 (shown schematically in FIG. 4A) in acollapsed shape within outer shaft 92. A plurality of control wires 97have an outer extremity 98 outside of inner shaft 94 and an innerextremity 100 extending through one or more lumens 102 and distal ports103 in inner shaft 94. Both outer portion 98 and inner portion 100extend proximally to the proximal end of delivery catheter 90. Outerextremities 98 are threaded through openings in the wall of stent 96 orare otherwise coupled thereto as described above so as to resistexpansion of stent 96 upon deployment. Control wires 97 thus form acontinuous loop from the proximal end of stent delivery catheter 90,through stent 96 and back to the proximal end of the catheter.

FIG. 4B illustrates this embodiment of delivery catheter 90 positionedin a vessel V and carrying plurality of stents 96′. Stents 96′ haveaxial projections 104 at their distal and proximal ends configured tointerleave when stents 96′ are collapsed within outer shaft 92 and whendeployed in vessel V. When outer shaft 92 is retracted to expose one ormore stents 96′, the expansion of stents 96′ can be resisted andcontrolled by maintaining tension on control wires 97. Tension may becontrollably relaxed to allow stents 96′ to expand into contact withlesion L, as shown in FIG. 4B. By controlling the expansion in this way,the axial spacing and rotational positions of adjacent stents 96′ may bemaintained so that gaps and overlaps are minimized and the interleavingof axial projections 104 is maintained. When stents 96′ are fullyexpanded, one end of each control wire 97 may be released at theproximal end of delivery catheter 90 while the other end is pulled toretract the control wires from stents 96′.

In a further embodiment, illustrated schematically in FIGS. 5A-B,delivery catheter 108 is constructed as described above except thatcontrol wires 110 are releasably coupled to the distal end of an innershaft 112 or to nose cone 114. In an exemplary embodiment, control wires110 have balls 116 at their distal ends configured to be received withinslots 118 on the outer surface of nosecone 114 (FIG. 5A) or on theproximal face of nosecone 114 (FIG. 5B; outer shaft not shown forclarity). Slots 118 have an enlarged portion 120 of sufficient size toreceive ball 116 and a narrow portion 122 through which balls 116 maynot pass. Inner shaft 112 is axially rotatable relative to control wires110. As in the embodiment of FIGS. 4A-B, with balls 116 held withinslots 118, tension may be maintained on control wires 110 to resistexpansion of stent 124. Stent 124 may be allowed to expand by graduallyrelaxing tension on control wires 110. Once stent 124 is fully expandedtension on control wires 110 may be fully relaxed and nosecone 114 thenrotated by rotating inner shaft 112, thereby allowing balls 116 to passthrough enlarged portions 120. Control wires 110 may then be withdrawnfrom the deployed stent 124. Nosecone 114 is then retracted or controlwires 110 advanced so as to reinsert balls 116 into slots 118. Nosecone114 is then rotated to align balls 116 with narrow portions 122, againsecuring the control wires to nosecone 114. Delivery catheter 108 maythen be repositioned to deploy additional stents.

Optionally, delivery catheter 108 may include a middle shaft or balloon126 over which stents 124 are positioned, as shown in FIG. 5A. In thiscase, inner shaft 112 is slidably and rotatably disposed in an innerlumen though middle shaft or balloon 126. If a balloon is included, itmay be used for pre-dilatation of lesions prior to stent deployment, orfor further expansion of stent 124 following deployment.

In the foregoing embodiment, control wires 110 will be constructed tohave sufficient stiffness to resist rotation, twisting or bending asnosecone 114 is rotated to release control wires 110. Maintaining sometension on control wires 110 as nosecone 114 is rotated may facilitatethe release process. In addition, control wires 110 will have sufficientcolumn strength to facilitate reinsertion into slots 118 followingdeployment of stents 124. Thus the size, material and geometry ofcontrol wires 110 will be selected to enable these actions whileproviding the desired level of control of stent expansion.

In a further embodiment of a stent delivery catheter according to theinvention, an expandable sleeve 130 is slidably positioned within outershaft 132 and carries stents 134 as shown in FIGS. 6A-C. A pusher shaft136 is slidable within sleeve 130 and engages the proximal-most stent134. An inner shaft 138 extends through pusher shaft 136 and has anosecone 140 fixed to its distal end. Sleeve 130, or at least a distalextremity thereof, may be a tube constructed of a resilient deformablematerial such as urethane or other medical grade elastomer, or may be atubular mesh, cage, grating, or other suitable structure of flexible andresilient polymer or metal such as stainless steel or Nitinol. Theelasticity and stiffness of sleeve 130 are selected to allow stents 134to expand at the desired rate when deployed from outer shaft 132 withoutexcessive axial or rotational displacement relative to each other or toouter shaft 132. Sleeve 130 is resiliently biased toward an unexpandedshape so that following stent deployment, sleeve 130 returns to agenerally tubular shape. Outer shaft 132 is constructed of a materialwith sufficient radial strength and stiffness to resist expansion ofstents 134 and sleeve 130, and may include a metallic or polymericbraid, ribs, rings or other structural reinforcement near its distal endfor such purpose.

The interior surface of sleeve 130 optionally may have surface featuressuch as bumps, scales, bristles, ribs, or roughness to enhance frictionwith stents 134. These features may be configured to have a grain suchthat they provide more friction against movement in the distal directionthan in the proximal direction, or vice versa. Further, such featuresmay be adapted to provide more friction when sleeve 130 is in anunexpanded shape than when it is expanded by stents 134. For example,bristles may be provided that point more in the proximal direction whensleeve 130 is in its unexpanded cylindrical shape, but which point moredistally or radially (perpendicular to the surface of sleeve 130) whensleeve 130 is expanded. This allows sleeve 130 to be more easilywithdrawn from stents 134 when stents 134 are deployed.

In order to deploy stents 134, delivery catheter 129 is positionedacross a vascular lesion so that nosecone 140 is disposed just distallyof the distal end of the lesion. Outer shaft 132 is then retracted toexpose the desired number of stents 134 (and the associated length ofsleeve 130) which will cover the length of the lesion, as shown in FIG.6B. As outer shaft 132 is retracted, stents 134 are allowed to expandinto contact with the lesion as shown in FIG. 6C. Sleeve 130 controlsthe rate of expansion and maintains the positions of stents 134 so theyare deployed precisely at the intended location. Once stents 134 arefully expanded, sleeve 130 may be retracted from between the stents andthe lesion until sleeve 130 is again disposed in outer shaft 132.Pressure is maintained on pusher shaft 136 during this process so thatthe stents 134 remaining in delivery catheter 129 are advanced to thedistal end of sleeve 130 and outer shaft 132. Delivery catheter 129 maythen be repositioned for deployment of additional stents at otherlocations.

Referring now to FIGS. 7A-B, in a further embodiment, a deliverycatheter 142 may be constructed largely as described in connection withFIGS. 6A-C, including an outer shaft 144, an expandable sleeve 146slidably disposed therein, a pusher shaft 148, and inner shaft 150. Aplurality of stents 152 are carried in expandable sleeve 146 (shown inFIG. 7B). In order to facilitate expansion, expandable sleeve 146includes a longitudinal slit 154 in at least a distal extremity thereof.When outer shaft 144 is retracted relative to sleeve 146, sleeve 146 maybe controllably expanded by axially twisting sleeve 146 such that theopposing edges 156 along longitudinal slit 154 pivot away from oneanother, forming a cone shape (FIG. 7B). In this way, the expansion ofstents 152 is further controllable after retraction of outer shaft 144by controlling the rate of twisting of sleeve 146. An actuator may beprovided at the proximal end of delivery catheter 142 to control suchtwisting. Optionally, sleeve 146 may have a helical thread on its outersurface that mates with a complementary thread on the interior of outershaft 144 such that sleeve 146 is automatically twisted as outer shaft144 is retracted. As in the embodiment of FIGS. 6A-C, following stentdeployment, sleeve 146 is retracted from the space between the deployedstents and the vessel wall and returned within outer shaft 144. Sleeve146 may be resiliently biased to return to its unexpanded configuration,or may be manually twisted back to an unexpanded shape by the operator.

In another embodiment, shown in FIGS. 8A-C, delivery catheter 160 isagain constructed much like delivery catheter 129 of FIGS. 6A-C,including an outer shaft 162, a slidable expandable sleeve 164 carryingstents 166, a pusher shaft 168, and an inner shaft 170. A nosecone 172is attached to the distal end of inner shaft 170 and has a concavity 174at its proximal end configured to receive the distal end of sleeve 164.A distal extremity of sleeve 164 includes a plurality of axial slits 176defining separate deflectable longitudinal beams 178. Sleeve 164includes at least two, preferably four, and as many as six, eight, ormore slits 176 to provide a corresponding number of longitudinal beams178. Longitudinal beams 178 are resiliently biased into an axialorientation wherein sleeve 164 is generally cylindrical. Longitudinalbeams 178 have sufficient stiffness against lateral deflection to resistand control the expansion of stents 166.

Advantageously, by containing the distal ends of longitudinal beams 178in concavity 174, outer shaft 162 may be retracted to expose the desirednumber of stents to cover a target lesion without immediate expansion ofstents 166, as shown in FIG. 8B. When the desired number of stents 166is exposed, inner shaft 170 may be advanced distally relative to sleeve164, releasing longitudinal beams 178 from concavity 174. This permitslongitudinal beams 178 to laterally deflect, allowing stents 166 toexpand, as shown in FIG. 8C. When full expansion is achieved,longitudinal beams 178 may be retracted from between stents 166 and thevessel wall. Longitudinal beams 178 then return to their undeflectedaxial orientation, allowing inner shaft 170 to be retracted so as toreturn the distal ends of longitudinal beams 178 into concavity 174.Inner shaft 170 and sleeve 164 may then be retracted into outer shaft162 while maintaining pressure on pusher shaft 168, thereby advancingadditional stents 166 toward the distal end of sleeve 164 for additionaldeployments.

In some embodiments of the stent delivery catheter of the invention, thestents themselves are configured to provide greater control andprecision in stent deployment. For example, FIGS. 9A-9B illustrates adelivery catheter 180 having a plurality of stents 182 disposed in anouter shaft 184. An inner shaft 186 with optional balloon 188 andnosecone 190 extends through outer shaft 184 and stents 182 and isaxially movable relative thereto. A pusher shaft (not shown) is slidablydisposed over inner shaft 186 and engages stents 182 for purposes ofdeploying stents 182 from outer shaft 186 and repositioning theremaining stents 182 within outer shaft 186, as in earlier embodiments.In this embodiment, stents 182 comprise a plurality of struts 191forming a series of rings 192 interconnected at joints 193. Each ring192 has a series of closed cells 194 interconnected circumferentiallyand having an “I” shape in the unexpanded configuration.

As outer shaft 184 is retracted to deploy one or more stents 182, atleast a distal ring 192′ is configured to expand into engagement withthe vessel wall before the entire length of the stent 182 is deployedfrom outer shaft 184 (FIG. 9A). Once in engagement with the lesion L invessel V, distal ring 192′ anchors stent 182 in position as theremainder of the stent is deployed (FIG. 9B), preventing “watermelonseeding” of the stent from the catheter. The axial length of stent 182,the length of each ring 192, the number of rings, the stiffness ofstruts 191, and the flexibility of joints 193 are all selected tooptimize this deployment behavior. Each stent 182 has at least two, andpreferably four or more rings 192, each ring being about 2-5 mm inlength, giving stent 182 an overall length of at least about 8-20 mm. Ofcourse, stents of shorter or longer length are also contemplated withinthe scope of the invention. Lesions longer than each stent 182 may betreated by deploying multiple stents 182 end-to-end. Advantageously,each stent 182 can be deployed precisely at a desired spacing from apreviously-deployed stent 182 because the distal ring 192′ of each stent182 can be first allowed to expand into engagement with the vessel atthe target location, anchoring the stent in position as the remainder isdeployed.

Rings 192 are preferably formed from a common piece of material and areintegrally interconnected at joints 193, making joints 193 relativelyrigid. In this embodiment, the majority of flexibility between rings 192is provided by struts 191 rather than by joints 193. Alternatively,joints 193 may comprise welded connections between rings 192 which arealso fairly rigid. As a further alternative, joints 193 may comprisehinge or spring structures to allow greater deflection between adjacentrings 192, as exemplified in FIGS. 10A-10B, described below.

In the embodiment of FIG. 10A-10B, stents 200 are constructed similarlyto stents 182 of FIGS. 9A-9B, including a plurality of interconnectedrings 202 having I-shaped cells 204. However, in this embodiment, someof rings 202 are interconnected by spring members 206 that may beelongated to increase the distance between rings 202 and that areresiliently biased into a shortened configuration to draw rings 202toward each other. In one embodiment, spring members 206 have awave-like shape and extend from the tip of an axial projection 208 onone ring 202 to a concave portion 210 between axial projections 208 onthe adjacent ring 202. Of course a variety of spring configurations andconnection locations are possible, including zig-zags, coils, spirals,accordian or telescoping structures, and the like. Further, resilientelongatable elastomeric elements may link the adjacent rings 202. In theillustrated embodiment, stent 200 comprises two pairs of rings 202, withthe rings of each pair interconnected by integral joints 212 as in FIGS.9A-B and the pairs of rings 202 being connected to each other by springmembers 206. Stents 200 may alternatively include two, three, five, sixor more rings 202, and spring members 206 may interconnect all or only aportion of rings 202.

Spring members 206 may be formed of the same or different material asthat of rings 202, depending upon the desired performancecharacteristics. In addition, spring members 206 may be biodegradable soas to erode and eventually disappear, leaving the adjacent pairs ofrings 202 unconnected.

During deployment, as outer shaft 184 is retracted to expose a stent200, the distal pair of rings 202′ first expands into engagement withlesion L in vessel V (FIG. 10A). Spring members 206 elongate to allowrings 202′ to fully expand without pulling the second pair of rings 202″from outer shaft 184. As retraction of outer shaft 184 continues, thesecond pair of rings 202″ expands and simultaneously is drawn towarddistal ring pair 182′ by contraction of spring members 206 (FIG. 10B).This results in a predictable and constant axial spacing between theadjacent pairs of rings 202. In addition, spring members 206 maintainrotational alignment of rings 202 to maintain the interleaving of axialprojections 208 without overlap. As in previous embodiments, multiplestents 200 may be deployed sequentially from delivery catheter 180 tocover longer lesions. The ability to precisely deploy each stent permitsthe relative axial spacing and rotational position of such stents to becontrolled to avoid excessive space or overlap.

In a further embodiment, shown schematically in FIGS. 11A-11C, adelivery catheter 216 has an outer shaft 218 carrying a plurality ofstents 220. An inner shaft 222 extends through outer shaft 218 to anosecone 224, and a pusher shaft 226 is slidably disposed over innershaft 222. An anchoring balloon 228 is mounted to inner shaft 222proximal to nosecone 224. Anchoring balloon 228 has an axial lengthsufficient to frictionally engage the wall of vessel V and remain stableso as to anchor delivery catheter 216 in place as further describedbelow. Preferably, anchoring balloon 228 has a length about equal to thelength of one of stents 220.

In use, outer shaft 218 is retracted so that a first stent 220′ isreleased therefrom and expands into engagement with lesion L (FIG. 11A).Anchoring balloon 228 is then inflated until it engages the interior ofstent 220′ (FIG. 11B). This not only stabilizes delivery catheter 216,but may be used to further expand stent 220′ and/or dilate lesion L tofirmly implant stent 220′. While keeping anchoring balloon inflatedwithin stent 220′, outer shaft 218 is further retracted to release asecond stent 220″, which expands into engagement with lesion L (FIG.11C). Advantageously, anchoring balloon 228 stabilizes delivery catheter216 and anchors it in position relative to first stent 220′ as secondstent 220″ is deployed. Second stent 220″ is thus deployable preciselyat the intended spacing and rotational position relative to first stent220′. Anchoring balloon 228 may then be deflated and retracted intoouter shaft 218, with pressure maintained upon pusher shaft 226 toreposition remaining stents 220 at the distal end of inner shaft 222.

FIGS. 11D-11F illustrate another embodiment of a delivery catheter 219in which a plurality of self-expanding stents 221 are slidably disposedover an elongated balloon 223. Balloon 223 preferably has a length aslong as the longest lesion that is to be treated with the device, e.g.50-200 mm. A pusher 225 is slidable relative to balloon 223 and has atubular distal portion 227 disposed over balloon 223 which engages theproximal-most stent 221P. A sheath 229 is slidably disposed over pusher225, stents 221 and balloon 223 and maintains stents 221 in a radiallycontracted configuration. In this embodiment, moderate pressure ismaintained within balloon 223 during deployment of stents 221 so thatthe balloon expands simultaneously with each stent. As shown in FIG.11B, as sheath 229 is retracted, a first stent 221A and a distal portionof balloon 223 are exposed. By maintaining moderate inflation pressurein balloon 223 as sheath 220 is retracted the exposed portion of balloon223 expands with the first stent 221A, inhibiting distal migration ofthe stent from delivery catheter 219. One or more additional stents 221may be deployed by further retraction of sheath 229, during whichballoon 223 remains expanded within first stent 221 anchoring thedelivery catheter 219 in position (not shown). As each additional stentis exposed from sheath 229, the pressure in balloon 223 causes it toexpand with the stent so as to control its rotational and axialposition. Of course, stents 221 may have any of a variety of differentconfigurations, including having open or closed cells, zig-zag orwave-shaped struts, and/or axially interleaving elements as describedabove.

Optionally, balloon 223 may have surface features or coatings on itsperiphery that enhance retention of stents 221 thereon. Such featuresmay include structures such as scales or protuberances that areactivated by pressurization of the balloon so that retention is lessenedwhen the balloon is deflated, but heightened when the balloon ispressurized. Following stent deployment, pressure can optionally beincreased in balloon 223 for post-dilation of stents 221 and the targetlesion L. Balloon 223 is then deflated and retracted within sheath 229as distal pressure is maintained against pusher 225, repositioningstents 221 near the distal end of balloon 223 within sheath 229 fordeployment at another location, as shown in FIG. 11C.

In a further embodiment, the stents in the delivery catheter of theinvention may releasably interconnect with one another and/or with thepusher shaft to enable greater control and precision during deployment.As illustrated in FIG. 12, delivery catheter 230 carries a plurality ofstents 232 having a structure much like that described above inconnection with FIGS. 9A-9B. However, in this embodiment, the axialprojections 234 extending distally and proximally from stents 232 areconfigured to interconnect with concavities 236 on adjacent stents 232until expanded. In one embodiment, axial projections 234 have enlargedheads 246 and concavities 236 have necks 248 that retain heads 246within concavities 236 in the unexpanded configuration. Pusher shaft 250has a distal end 252 having projections 254 and concavities 256 likethose of stents 232, thus being able to interconnect with theproximal-most stent 232′. When a stent 232″ expands, the interconnectingstructures thereon are configured to separate from the adjacent stent orpusher shaft, thus releasing the deployed stent 232″ from deliverycatheter 230. In the example shown, as stent 232″ expands, heads 246″contract in size while necks 248″ enlarge, thereby allowing heads 246″on the expanded stent to be released from concavities 236 in theadjacent unexpanded stent, and vice versa. By exerting traction onpusher shaft 250 during the deployment process, the line of stents 232is kept from moving distally relative to outer shaft 231, thuspreventing the deployed stent 232″ from “watermelon seeding” as itexpands.

Various types of interconnecting structures between adjacent stents andbetween the stents and the pusher shaft are possible within the scope ofthe invention, including those described in co-pending application Ser.No. 10/738,666, filed Dec. 16, 2003, which is incorporated herein byreference. Such interconnecting structures may also be breakable orfrangible to facilitate separation as the stent expands. In addition, amechanism such as an expandable balloon or cutting device may bedisposed at the distal end of delivery catheter 230 to assist inseparating stents 232 upon deployment. Further, the interconnectionsbetween stents may be different than the interconnection between theproximal-most stent and the pusher shaft. For example, the pusher shaftmay have hooks, magnets, or other mechanisms suitable for releasablyholding and maintaining traction on the proximal end of a stent until itis deployed.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, improvements andadditions are possible without departing from the scope thereof, whichis defined by the claims.

1. A prosthesis delivery catheter comprising: an outer shaft having a first lumen; a plurality of self-expanding tubular prostheses carried within the first lumen, the prostheses being adapted to radially expand upon deployment from the first lumen; a deployment mechanism for deploying a selected number of the prostheses from the first lumen; and a control member interactive with the prostheses to control expansion of the prostheses when the prostheses are deployed from the first lumen.
 2. The prosthesis delivery catheter of claim 1 wherein the control member comprises a plurality of axially-extending wires, the prostheses being coupled to the wires and axially slidable thereon, the wires being radially deflectable to allow controlled expansion of the prostheses.
 3. The prosthesis delivery catheter of claim 2 wherein the wires have free distal ends configured to move radially outward as the prostheses expand.
 4. The prosthesis delivery catheter of claim 3 wherein the distal ends are retractable into the outer shaft following deployment of the selected number of prostheses.
 5. The prosthesis delivery catheter of claim 2 wherein the prostheses have sidewalls with a plurality of openings, the wires being threaded through the openings.
 6. The prosthesis delivery catheter of claim 2 wherein the wires form a loop extending around the outside of the prostheses and through the inside of the prostheses.
 7. The prosthesis delivery catheter of claim 6 wherein the wires can be withdrawn from around the prostheses following deployment thereof.
 8. The prosthesis delivery catheter of claim 7 wherein at least one end of each wire is releasable to allow the wire to be withdrawn following prosthesis deployment.
 9. The prosthesis delivery catheter of claim 8 further comprising an inner shaft disposed in the first lumen, the prostheses being slidably disposed around the inner shaft, wherein a distal end of each wire is releasably coupled to the inner shaft.
 10. The prosthesis delivery catheter of claim 9 further comprising a nosecone attached to the inner shaft distally of the prostheses, the distal end of each wire being releasably coupled to the nosecone.
 11. The prosthesis delivery catheter of claim 9 wherein the inner shaft has an inner lumen and at least one port in communication with the inner lumen, the wires being slidably disposed through the inner lumen and the port.
 12. The prosthesis delivery catheter of claim 1 wherein the control member comprises a sleeve disposed around the prostheses, the sleeve being expandable to allow controlled expansion of the prostheses.
 13. The prosthesis delivery catheter of claim 12 wherein the sleeve is elastomeric.
 14. The prosthesis delivery catheter of claim 12 wherein the sleeve is slidable relative to the outer shaft.
 15. The prosthesis delivery catheter of claim 12 wherein the sleeve has at least one longitudinal slit therein, the sleeve expanding by splitting at the longitudinal slit.
 16. The prosthesis delivery catheter of claim 15 wherein the sleeve comprises a plurality of longitudinal sections separated by longitudinal slits, the longitudinal sections being deflectable outwardly to allow controlled expansion of the prostheses.
 17. The prosthesis delivery catheter of claim 16 further comprising a retainer releasably coupled to the longitudinal sections to selectively prevent radial deflection thereof.
 18. The prosthesis delivery catheter of claim 17 further comprising an inner shaft slidably disposed through the first lumen and having a distal end, the retainer being coupled to the distal end.
 19. The prosthesis delivery catheter of claim 15 wherein the sleeve expands by forming a cone shape that flares in the distal direction.
 20. The prosthesis delivery catheter of claim 19 wherein the sleeve has a pair of opposing edges bordering the longitudinal slit, the cone shape being formed by moving the edges at an angle relative to each other.
 21. The prosthesis delivery catheter of claim 1 wherein the deployment mechanisms comprises a pushing element slidably disposed in the first lumen, the pushing element being in engagement with at least one of the prostheses to advance the prostheses distally relative to the outer shaft.
 22. The prosthesis delivery catheter of claim 21 wherein the plurality of prostheses are releasably interconnected to each other.
 23. The prosthesis delivery catheter of claim 22 wherein the control member comprises an interconnection structure on the pushing element, the interconnection structure being releasably coupled to at least one of the prostheses to resist distal movement of the prostheses relative to the outer shaft.
 24. The prosthesis delivery catheter of claim 1 wherein the control member is configured to maintain rotational position of the prostheses relative to each other.
 25. A prosthesis delivery catheter for delivering prostheses into a vessel lumen comprising: an outer shaft having a first lumen; a plurality of self-expanding tubular prostheses carried within the first lumen, the prostheses being adapted to radially expand upon deployment from the first lumen; a deployment mechanism for deploying a selected number of the prostheses from the first lumen; and a anchor member adapted to engage the vessel to limit movement of the outer shaft relative thereto when a prosthesis is being deployed.
 26. The prosthesis delivery catheter of claim 25 wherein the anchor member comprises an expandable member mounted on an inner shaft, the inner shaft being slidably disposed in the first lumen.
 27. The prosthesis delivery catheter of claim 26 wherein expandable member comprises a balloon.
 28. The prosthesis delivery catheter of claim 26 wherein the expandable member is configured to expand within a deployed prosthesis in the vessel lumen.
 29. The prosthesis delivery catheter of claim 28 wherein the expandable member is configured to remain expanded within the deployed prosthesis while a second prosthesis is deployed adjacent to the deployed prosthesis.
 30. A prosthesis delivery catheter for delivering prostheses into a vessel lumen comprising: an outer shaft having a first lumen; a plurality of self-expanding tubular prostheses carried within the first lumen, the prostheses being adapted to radially expand upon deployment from the first lumen, each prosthesis comprising a distal portion and proximal portion, the distal portion being configured to expand into engagement with the vessel while the proximal portion is at least partially disposed in the first lumen; and a deployment mechanism for deploying a selected number of the prostheses from the first lumen.
 31. The prosthesis delivery catheter of claim 30 wherein the distal and proximal portions are interconnected by at least one spring member, the spring member having a retracted shape and an elongated shape and being biased into the retracted shape, wherein deployment of the distal portion into the vessel elongates the spring into the elongated shape.
 32. The prosthesis delivery catheter of claim 31 wherein deployment of the proximal portion into the vessel allows the spring to return at least partially to the retracted shape to draw the proximal portion toward the distal portion.
 33. The prosthesis delivery catheter of claim 30 wherein the distal portion is configured to engage the vessel prior to deployment of the proximal portion so that the prosthesis remains in a generally constant position relative to the catheter as the proximal portion is deployed.
 34. A method of delivering one or more prostheses to a treatment site in a vessel comprising: positioning a delivery catheter at the treatment site, the delivery catheter carrying a plurality of self-expanding prostheses; selecting a desired number of the prostheses to deploy; deploying the desired number of prostheses from the delivery catheter into the vessel, each prosthesis expanding into contact with the vessel upon deployment; and controlling the axial displacement of each of the selected number of prostheses relative to the delivery catheter during the deployment thereof.
 35. The method of claim 34 wherein the axial displacement is controlled by an expandable sleeve disposed around the desired number of prostheses.
 36. The method of claim 35 further comprising retracting the sleeve from around the prostheses after the prostheses have been deployed.
 37. The method of claim 34 wherein the axial displacement is controlled by a plurality of wires coupled with the desired number of prostheses.
 38. The method of claim 37 further comprising retracting the wires from the prostheses after the prostheses have been deployed.
 39. The method of claim 37 wherein the wires are threaded through openings in each of the prostheses.
 40. The method of claim 34 further comprising controlling the rotational displacement of the selected number of prostheses relative to the delivery catheter during the deployment thereof.
 41. The method of claim 34 wherein the axial displacement is controlled by expanding an expandable member in the vessel during deployment of at least a portion of the desired number of prostheses.
 42. The method of claim 34 wherein the axial displacement is controlled by expanding a distal portion of a first of the prostheses into engagement with the vessel while a proximal portion of the first of the prostheses remains in the delivery catheter, then expanding the proximal portion of the first of the prostheses into engagement with the vessel.
 43. The method of claim 34 wherein the prostheses are releasably interconnected while in the delivery catheter.
 44. The method of claim 43 wherein the axial displacement is controlled by connecting at least one of the prostheses to a restraining member in the delivery catheter.
 45. The method of claim 43 wherein the selected number of prostheses detach from the prostheses remaining in the delivery catheter upon deployment. 